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This case study of biogas power plant is designed in accordance with the existing energy policy that recognizes producers of energy from renewable sources as producers with privileged status and guarantees the purchase of energy at subsidized prices. The investor company revised its own energy policy and aligned it with the priorities of sustainable energy policy of Serbia. The paper presents an analysis of biogas power plant output (electrical and thermal energy), balance, sale, and potential prices on the market that are consistent with the incentives of energy policy of Serbia. In addition, special emphasis is given to the revenues that a biogas power plant realizes by using another mechanism of energy policy, which promotes gaining revenues by reducing pollution of the atmosphere. The authors also show the procedure, costs, and expected effects from the qualification of this power plant project for the Clean Development Mechanism project categories. Investing in a biogas power plant in Serbia costs 950 000 euros and is financed from the European Bank for Reconstruction and Development (EBRD) funds for the Western Balkans. Analysis of the parameters described in the paper can serve as a guide and example for potential investors in this field.

The curing process of thermosetting resins plays a key role on the final quality of the composite material components. Soft computing techniques proved to be an efficient method to control and optimize the curing process, replacing the conventional experimental and numerical approaches. In this paper artificial neural network (ANN) and fuzzy logic control (FLC) were implemented together to predict and control the temperature and degree of cure profile during the autoclave curing process. The obtained outcomes proved the capability of ANNs and FLC with respect to the hard computing methods.

Biomass is a renewable energy source with the highest potential to contribute in meeting energy needs and providing a secure and sustainable energy supply. For combustion of biogas (low calorific gas), an efficient technology is needed. It should provide stable combustion with low emission of pollutants such as CO and NOx over a wide operating range. This paper presents the experimental investigation on emission and stability of a premixed dual feed biogas swirl combustor with a pilot burner. For the experimental investigation, swirlers with swirl numbers 1.13 for the main burner and 1.98 for the pilot burner were used. The tests were performed at atmospheric conditions. The effects of carbon dioxide content, nominal thermal power, and equivalence ratio were analyzed and briefly discussed.

In this paper, the authors intend to show that environmental taxes are an economic instrument that entirely supports the principles of sustainable development and has impact on balanced improvement of all its four pillars (economic, ecological, social, and institutional). Environmental taxes provide a flexible and cost-effective means for reinforcing the polluter-pays principle and for reaching environmental policy objectives. Enforcement of environmental taxes (and penalties) simultaneously generates multiple values-it stimulates ecologically acceptable production, generates budget revenue, and stimulates socially responsible behavior. The subject of the analysis is determination of environmental taxes in the European Union (EU) member states in total amount and as a percentage of Gross Domestic Product (GDP), as well as monitoring of their trend in the period 2005-2010. To obtain a broad picture, results collected for EU-27 region have been compared with data for sample countries worldwide, including Brazil, Russia, India, China, and South Africa (BRICS) countries. The revenue from environmental taxes in the EU-27 is not negligible, amounting to about 3% of total revenues. The highest tax revenue as a percent of GDP was noted in Denmark-9% on average. Environmentally related revenues and their percent of GDP in sample countries reported diverse results. In the USA, China, and India, environmentally related revenue as a percent of GDP stood at around 1%, with a downward trend in time. The highest tax revenue as a percent of GDP was recorded in Turkey, Russia, South Africa, and Brazil, 4% on average, with an upward trend in time. However, increasing revenues from environmental taxes should be interpreted with caution. The increases may be caused by the introduction of new taxes or an increase in tax rates, or alternatively may be linked to an increase in the tax base.

In this paper we give error estimates for quadrature rules with maximal trigonometric degree of exactness with respect to an even weight function on (-pi, pi) for integrand analytic in certain domain of complex plane.

In this paper we report results of structural, spectroscopic, and magnetic investigations of MgFe2O4 nanoparticles prepared by soft mechanochemical synthesis. MgFe2O4 nanoparticles crystallize in Fd3m space group with mixed cation distribution and reduced percentage of Fe3+ at tetrahedral (8a) sites. Discrepancy in the cation distribution compared to that in the bulk Mg-ferrite is one of the highest known. X-ray line broadening analysis reveals crystallite size and strain anisotropy. The saturation magnetization, M-sat=62 emu/g measured at 5 K is twice higher than that found in the bulk counterparts. Such high value of M-sat is attributed to the low value of cation inversion parameter (delta=0.69), to the core/shell structure of the nanoparticles and to the surface/volume ratio. Moumlssbauer spectrum collected at room temperature reveals ferrimagnetic ordering between Fe3+ ions in 8a and 16d sites, while zero-field-cooled (ZFC) and field-cooled (FC) M(T) measurements were shown superparamagnetic state above 350 K.

In this paper we report results of structural, spectroscopic, and magnetic investigations of MgFe2O4 nanoparticles prepared by soft mechanochemical synthesis. MgFe2O4 nanoparticles crystallize in Fd3m space group with mixed cation distribution and reduced percentage of Fe3+ at tetrahedral (8a) sites. Discrepancy in the cation distribution compared to that in the bulk Mg-ferrite is one of the highest known. X-ray line broadening analysis reveals crystallite size and strain anisotropy. The saturation magnetization, M-sat=62 emu/g measured at 5 K is twice higher than that found in the bulk counterparts. Such high value of M-sat is attributed to the low value of cation inversion parameter (delta=0.69), to the core/shell structure of the nanoparticles and to the surface/volume ratio. Moumlssbauer spectrum collected at room temperature reveals ferrimagnetic ordering between Fe3+ ions in 8a and 16d sites, while zero-field-cooled (ZFC) and field-cooled (FC) M(T) measurements were shown superparamagnetic state above 350 K.

In this paper we report results of structural, spectroscopic, and magnetic investigations of MgFe2O4 nanoparticles prepared by soft mechanochemical synthesis. MgFe2O4 nanoparticles crystallize in Fd3m space group with mixed cation distribution and reduced percentage of Fe3+ at tetrahedral (8a) sites. Discrepancy in the cation distribution compared to that in the bulk Mg-ferrite is one of the highest known. X-ray line broadening analysis reveals crystallite size and strain anisotropy. The saturation magnetization, M-sat=62 emu/g measured at 5 K is twice higher than that found in the bulk counterparts. Such high value of M-sat is attributed to the low value of cation inversion parameter (delta=0.69), to the core/shell structure of the nanoparticles and to the surface/volume ratio. Moumlssbauer spectrum collected at room temperature reveals ferrimagnetic ordering between Fe3+ ions in 8a and 16d sites, while zero-field-cooled (ZFC) and field-cooled (FC) M(T) measurements were shown superparamagnetic state above 350 K.

In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from -50 to 50 degrees C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 degrees C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 degrees C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.

In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from -50 to 50 degrees C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 degrees C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 degrees C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.